 /*******************************************************************************
  * Copyright (c) 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.internal.registry;

 import org.eclipse.core.internal.registry.osgi.Activator;
 import org.osgi.framework.Bundle;
 import org.osgi.service.packageadmin.PackageAdmin;
 import org.osgi.util.tracker.ServiceTracker;

 public class BundleHelper {

     private ServiceTracker bundleTracker = null;

     private static final BundleHelper singleton = new BundleHelper();

     public static BundleHelper getDefault() {
         return singleton;
     }

     /**
      * Private constructor to block instance creation.
      */
     private BundleHelper() {
         super();
     }

     private PackageAdmin getPackageAdmin() {
         if (bundleTracker == null) {
             bundleTracker = new ServiceTracker(Activator.getContext(), PackageAdmin.class.getName(), null);
             bundleTracker.open();
         }
         return (PackageAdmin) bundleTracker.getService();
     }

     public Bundle getBundle(String symbolicName) {
         PackageAdmin packageAdmin = getPackageAdmin();
         if (packageAdmin == null)
             return null;
         Bundle[] bundles = packageAdmin.getBundles(symbolicName, null);
         if (bundles == null)
             return null;
         //Return the first bundle that is not installed or uninstalled
 for (int i = 0; i < bundles.length; i++) {
             if ((bundles[i].getState() & (Bundle.INSTALLED | Bundle.UNINSTALLED)) == 0) {
                 return bundles[i];
             }
         }
         return null;
     }

     public Bundle[] getHosts(Bundle bundle) {
         PackageAdmin packageAdmin = getPackageAdmin();
         if (packageAdmin == null)
             return null;
         return packageAdmin.getHosts(bundle);
     }

 }

